The proposed research involves the development of many new C-C and C-N bond forming reactions for eventual application to the total synthesis of pharmacologically significant materials, specifically: a) Stereocontrolled additions of various allyltin reagents to Beta-alkoxyaldehydes; b) Stereocontrolled additons of various allyltin reagents to Alpha-alkoxyaldehydes, c) Stereocontrolled additions of various allyltin reagents to Alpha-Beta-dialkoxyaldehydes, with stereochemical control formally exerted by either the Alpha or Beta-alkoxy group, d) The extension of the chemistry above aldimines, and Alpha and Beta-alkoxy aldimines. e) Asymmetric synthesis of homoallyl amines from readily available chiral aldimines, f) Further studies on new "one electron" C-C bond forming processes, g) Stereocontrolled additions of heteroatom or carbon nucleophiles to various Gamma-substituted unsaturated ketones, estaers, and thiol esters, h) Mechanistic investigations of the factors controlling the above processes, and i) Application of the foregoing to the synthesis of medicinally important materials, specifically pyrrolizidne alkaloids, calcimycin, the herbimycins and macbecins, and the mitomycins. It should be noted that perhaps the most significant aspect of the proposed work is its almost universal applicability to the synthesis of biologically active materials.